TWI718324B - Pipe joint - Google Patents

Abstract

The utility model provides a pipe joint for use under ultra-high pressure conditions without the diameter of the joint becoming relatively large.

A pipe joint is provided with: first and second joint members having fluid passages communicating with each other; and a gasket interposed between the abutting end surfaces of the first and second joint members, and the first and second joint members A ring-shaped sealing protrusion is formed on the abutting end surface of the, which is characterized by setting the inner diameter of the first and second joint members as D ₁ , the inner diameter of the gasket as D ₂ , the diameter of the sealing protrusion as D ₃ , and the When the outer diameter of the sheet is set to D ₄ , the coefficient F specified by formula (1) is below 0.4, formula (1): F=(D ₃ ² -D ₁ ² )/(D ₄ ² -D ₂ ² ) .

Description

Pipe joint

The present invention relates to a pipe joint, in particular to a pipe joint that plastically deforms a gasket for surface seal.

The pipe joint disclosed in Patent Document 1 for plastically deforming a gasket for surface sealing is well known. It includes: a tubular first joint member and a tubular second joint member, which have fluid passages communicating with each other; an annular gasket The sheet is interposed between the right end surface of the first joint member and the left end surface of the second joint member; and the holder, which holds the annular gasket, and is held on the first joint member; The member side is screw-fitted to the nut of the first joint member, and the second joint member is fixed to the first joint member.

With regard to this type of connector, due to its high sealing performance, it has been mainly used in the field of semiconductor manufacturing equipment.

On the other hand, in recent years, due to the development of the fuel cell vehicle field, joints for the purpose of supplying ultra-high pressure hydrogen are in great demand, and various types of joints are also under discussion.

The ultra-high pressure resistance required in these technical fields generally refers to the ability to withstand pressures above 100 MPa, and in the (Japan) High Pressure Gas Security Law, it is also required to pass a pressure test of 1.25 times the operating pressure.

Prior art literature Patent literature

Patent Document 1 Japanese Patent No. 3876351

In the case of using the above-mentioned conventional pipe joints under ultra-high pressure conditions, there is a problem of leakage.

The purpose of the present invention is to provide a pipe joint suitable for use under ultra-high pressure conditions.

The pipe joint of the present invention includes: first and second joint members having fluid passages communicating with each other; and a gasket interposed between the abutting end surfaces of the first and second joint members, and the first and second joint members A ring-shaped sealing protrusion is formed on the abutting end surface of the member, characterized in that the inner diameter of the first and second joint members is set to D ₁ , the inner diameter of the gasket is set to D ₂ , and the diameter of the sealing protrusion is set to D ₃ , When the outer diameter of the gasket is set to D ₄ , the coefficient F specified by the following formula (1) is 0.4 or less.

Formula (1): F=(D ₃ ² -D ₁ ² )/((D ₄ ² -D ₂ ² )

The inventor of the present case conducted a finite element analysis on the conditions under which the ultra-high pressure fluid flows through the fluid passages inside the first and second joint members, and found that the deformation of the gasket would affect the occurrence of leakage. It was further discovered that _{the combination index of D 1} to D ₄ below a certain value can bring advantageous effects, and finally the invention was developed and completed.

The pressure resistance performance of the pipe joint can be estimated to be related to the deformation of the gasket and the deformation of the joint member.

First, the amount of deformation of the gasket can be estimated to depend on the rigidity of the gasket. Because the higher the rigidity of the gasket, the smaller the deformation of the gasket caused by the internal pressure. If the thickness of the gasket is regarded as constant, the internal pressure P ₁ when the inner wall of the cylindrical tube begins to yield and deform is proportional to the rigidity of the cylindrical tube, so it can be presumed to be and (D ₄ ² -D ₂ ² ) Is proportional.

Furthermore, the deformation of the joint member is caused by the internal pressure acting on the abutting end surface of the joint member. Therefore, it can be estimated that the amount of deformation of the joint member and the diameter D ₃ of the sealing protrusion receiving the pressure from the high-pressure fluid and the first and _{The area of the ring pinched by the inner diameter D 1} of the second joint member is _{inversely proportional, and the internal pressure P 2} when the abutting end faces of the first and second joint members begin to yield deformation can be estimated to be the sum (D ₃ ² -D ₁ ² ) Inversely proportional.

Therefore, since the deformation of the gasket and the deformation of the joint member occur at the same time, it can be estimated that the pressure resistance of the gasket and the coefficient F=(D ₃ ² -D ₁ ² )/(D ₄ ² -D ₂ ² ) are based on The negative relationship is proportional. In fact, by the finite element method, it is found that F is preferably 0.4 or less.

In addition, D ₁ is practically limited due to the pressure or flow rate of the high-pressure fluid flowing, and D ₄ is practically limited due to the physical size of the pipe joint. Due to this practical limitation, the lower limit of the coefficient F In reality, it cannot be set below a certain value.

By adjusting the diameter D of the first and second joint member _1, the inner diameter D ₂ of the spacer, the diameter D of the seal _{projection. 3} and the outer diameter D of the _{spacer. 4,} to provide a pipe coupling suitable for EHV specifications .

1‧‧‧The first joint component

1a‧‧‧Inner circumference of the first joint member

2‧‧‧Second joint member

2a‧‧‧Inner circumference of the second joint member

3‧‧‧Gasket

3a‧‧‧Inner circumference of gasket

3b‧‧‧Removal prevention part

4‧‧‧Nut

5‧‧‧Retainer

6‧‧‧Ball bearing

7‧‧‧Annular sealing protrusion

8‧‧‧Annular sealing protrusion

9‧‧‧Over tightening to prevent protrusions

10‧‧‧Over tightening to prevent protrusions

11‧‧‧Inward flange

12‧‧‧Female thread

13‧‧‧Outward flange

14‧‧‧Male thread

Fig. 1 is a longitudinal sectional view of an embodiment of the pipe joint of the present invention.

Fig. 2 is a schematic diagram of a model for simulating stress-deformation when an internal pressure is applied to the pipe joint of Fig. 1.

Figure 3 is a graph showing the relationship between the pressure P and the coefficient F when the gasket begins to detach.

Fig. 4 is a graph showing the relationship between the pressure P and the coefficient F when the adhesion between the gasket and the joint member disappears.

Fig. 5 is a graph showing the relationship between the displacement of the gasket and the coefficient F when the adhesion between the gasket and the joint member disappears.

Embodiment of the invention

Hereinafter, the embodiments of the present invention will be exemplarily described in detail with reference to the accompanying drawings. However, as long as the dimensions, materials, shapes, and relative arrangements of the components contained in this embodiment are not specifically described, it does not mean that the scope of the present invention is limited to the description conditions, but merely simple Illustrative example.

The pipe joint is provided with: a tubular first joint member (1) and a tubular second joint member (2), which have fluid passages communicating with each other; an annular gasket (3), inserted in the first joint member (1) Between the right end surface of the second joint member (2) and the left end surface of the second joint member (2); and the holder (5) for holding the annular gasket (3), and is held by the first joint member (1), and by The second joint member (2) is fixed to the first joint member (1) by a nut (4) screwed and fitted to the first joint member (1) from the second joint member (2) side. In each joint member(1)(2) An annular sealing protrusion (7) (8) is respectively formed in the radial direction of the abutting end surface of the abutting end surface, and an annular over-locking prevention protrusion (9) (10) is respectively formed on the outer periphery of the abutting end surface.

The two end surfaces of the gasket (3) are formed as flat surfaces at right angles to the axial direction. The outer peripheral surface of the gasket (3) is provided with an anti-falling part (3b) formed by an outward flange.

Both joint components (1), (2) and gasket (3) are made of SUS316L.

An inward flange (11) is formed at the right end of the nut (4), and the flange (11) is fitted around the second joint member (2). A female thread (12) is formed on the inner periphery of the left end of the nut (4), and the female thread is screw-fitted to the male thread (14) formed on the right side of the first joint member (1). An outward flange (13) is formed on the outer periphery of the left end of the second joint member (2), and a thrust ball bearing for preventing simultaneous rotation is interposed between it and the inward flange (11) of the nut (4) (6).

Each ring-shaped protrusion (9) (10) for preventing over-locking is more protruding from the side of the gasket (3) in the left-right direction than the annular sealing protrusions (7) (8). It is necessary to lock it further from a proper locking state. At this time, the sealing protrusions (7) and (8) will push the holder (5) from both sides.

When the nut (4) is re-locked from the manual locking state with a wrench or the like, the gap between the over-locking prevention protrusion (9) (10) and the holder (5) becomes 0, which is the resistance to locking The force will become very large, so it can prevent over-locking.

The inner circumference (1a) of the first joint member (1), the inner circumference (2a) of the second joint member (2), and the inner circumference (3a) of the gasket form a fluid passage.

When the inner diameter of the first and second joint members is set to D ₁ , the inner diameter of the gasket is set to D ₂ , the diameter of the sealing protrusion is set to D ₃ and the outer diameter of the gasket is set to D ₄ , the coefficient is preferably F=(D ₃ ² -D ₁ ² )/(D ₄ ² -D ₂ ² ) is 0.4 or less. Furthermore, the coefficient F is more preferably 0.3 or less.

Here, D ₃ is the diameter of the central point of the most protruding part connecting the annular sealing protrusions (7) (8), and D ₄ is the outer diameter of the annular gasket (3) that does not include the anti-falling portion (3b) path.

If the coefficient F is 0.4 or less, the deformation of the gasket tends to be suppressed. If the coefficient F is 0.3 or less, the deformation of the gasket can be suppressed very low, which is more desirable.

Fig. 2 is a schematic diagram of a model for simulating stress-deformation when internal pressure is applied to a pipe joint. It is based on a gasket (3) pinched between the first pipe joint (1) and the second pipe joint (2), and the inner diameter of the inner circumference (1a) (2a) is set to D ₁ , the inner circumference The inner diameter of (3a) is set to D ₂ , the diameter of the annular sealing protrusion (7) (8) is set to D ₃ , and the outer diameter of the gasket (3) but not the outer diameter of the anti-drop part (3b) Set to D ₄ for analysis.

(Test Example 1)

The material of the components is stainless steel, and finite element analysis is carried out. The following table [Table 1] shows the _{values of D 1} to D ₄ , the coefficient F at this value, and the pressure P at the beginning of the separation of the gasket (3). A graph showing the relationship between F and P is shown in FIG. 3. In addition, the broken line is an approximate straight line.

Observing Figure 3, it can be seen that the relationship between the coefficient F and the pressure P at which the gasket starts to separate is linear, and the coefficient F is an appropriate coefficient.

(Test Example 2)

Next, the material of the components is stainless steel, and finite element analysis is performed. The following table [Table 2] shows the _{values of D 1} to D ₄ , the coefficient F at this value, and the pressure P when the adhesion between the gasket (3) and the joint member (1) (2) disappears, The graph showing the relationship between F and P is shown in FIG. 4. In addition, the broken line is an approximate straight line.

Observing Figure 4, since this test example analyzes the pressure at which the adhesion between the gasket and the joint member begins to disappear, compared to Figure 3, although the approximate straight line slope becomes smaller, the coefficient F and adhesion begin to disappear. The relationship of P still maintains a very high linear relationship as in Figure 3, so the appropriateness of the coefficient F can be understood.

(Test Example 3)

Next, the finite element analysis was performed under the same conditions as in Test Example 2. The following table [Table 3] shows the _{value of D 1} to D ₄ , the coefficient F at this value, and the inner part of the gasket when the adhesion between the gasket (3) and the joint member (1) (2) disappears. The radial displacement, the displacement of the outer diameter of the gasket, and the displacement of the annular sealing protrusions (7) (8) of the gasket, and a graph showing the relationship between F and displacement are shown in FIG. 5. In addition, the unit of displacement is mm.

In Fig. 5, the displacement of the inner diameter of the gasket is represented by a solid line, the displacement of the outer diameter of the gasket is represented by a long dashed line, and the displacement of the annular sealing protrusion position of the gasket is represented by a thin dashed line. In the interval where the coefficient F is 0.66 to 0.52, any displacement increases as the coefficient F decreases; in the interval where the coefficient F is 0.52 to 0.40, any displacement does not change with the coefficient F, and is almost constant; When the coefficient F is between 0.40 and 0.27, any displacement decreases as the coefficient F decreases; when the coefficient F is less than 0.27, any displacement becomes the smallest and maintains a certain state.

Since the smaller the displacement, the more beneficial it is to improve the pressure resistance, so a coefficient F of 0.4 or less for the reduction of displacement steering is better. Furthermore, it is better to minimize the displacement and maintain a constant coefficient F of 0.3 or less.

Industrial possibilities

Regarding pipe joints for ultra-high pressure piping, the present invention can provide compact pipe joints with optimal shapes.

1‧‧‧The first joint component

1a‧‧‧Inner circumference of the first joint member

2‧‧‧Second joint member

2a‧‧‧Inner circumference of the second joint member

3‧‧‧Gasket

3a‧‧‧Inner circumference of gasket

3b‧‧‧Removal prevention part

4‧‧‧Nut

5‧‧‧Retainer

6‧‧‧Ball bearing

7‧‧‧Annular sealing protrusion

8‧‧‧Annular sealing protrusion

9‧‧‧Over tightening to prevent protrusions

10‧‧‧Over tightening to prevent protrusions

11‧‧‧Inward flange

12‧‧‧Female thread

13‧‧‧Outward flange

14‧‧‧Male thread

Claims (1)

A pipe joint is provided with: first and second joint members having fluid passages communicating with each other; and a gasket interposed between the abutting end surfaces of the first and second joint members, and the first and second joint members A ring-shaped sealing protrusion is formed on the abutting end surface of the member, characterized in that the inner diameter of the first and second joint members is set to D ₁ , the inner diameter of the gasket is set to D ₂ , and the diameter of the sealing protrusion is set to When it is D ₃ and the outer diameter of the aforementioned gasket is set to D ₄ , the coefficient F defined by the following formula (1) is 0.4 or less, and the formula (1): F=(D ₃ ² -D ₁ ² )/(D ₄ ² -D ₂ ² ).

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